Fire and rain hammer NZ's South Island

At least four houses have been destroyed on the southern outskirts of Christchurch as a grass fire, fanned by strong winds, tore through hedgerows, nurseries, farm buildings and a chicken farm.

Despite heavy rain around most of the South Island this week, dry conditions and a strong northwester hampered firefighters' efforts to contain a big fire around the Shands Road area in Prebbleton on Thursday afternoon.

Ten people were reportedly rescued from the area as one house was destroyed by fire and three were in flames.

Cordons were preventing residents returning to their houses, while helicopters and firefighters tried to quell the fire.

They had it under control by 8pm (1800 AEDT) but were expected to continue dampening down through the night. Hedges were still smouldering.

Selwyn District Mayor Kelvin Coe said it was the biggest fire he had seen in the district.

"Some evacuations were rather hastily done, but everyone has been accounted for," he told AAP.

As well as the four houses, a number of structures, such as storage sheds and nurseries had suffered.

Mr Coe was unsure if the affected chicken farm had housed any birds.

Several families would spend the night elsewhere until the damage to their houses could be assessed on Friday, he said.

Police on Thursday night were warning people to stay away from the low-lying bank areas of all Canterbury rivers, after they received reports that a large surge of water was visible from the air moving down the Waimakariri River.

Inspector Trevor Cross of police southern communications later said the surge may have actually been a combination of more flow and discoloured water.

However, Canterbury rivers were still very high and people should stay away from river banks and mouths, he said.

It followed "mini tornadoes" in Kaikoura in the morning, one ripping the roof off a house.

Further north, Air New Zealand cancelled nine regional flights in and out of Wellington as gales blasted the capital.

However, the MetService says the wet and blustery weather is set to turn more benign on Friday.

It had predicted gusts of up to 150km/h in some parts of Canterbury on Thursday and gusts of 140km/h in Wellington, Wairarapa and the Marlborough Sounds.

One wind gust of 230km/h was recorded at the Mt Hutt summit, while there have been gusts of about 120km/h in the Wellington suburb of Kelburn.

More than 15,000 lightning strikes had been detected in one 24-hour period between Wednesday and Thursday.

The New Zealand Transport Agency says all South Island roads closed by slips and washouts on Thursday are expected to be reopened on Friday, as contractors work to clear slips, repair washouts and clear debris.